Jack stands for use in automobile repair are designed to support a vehicle axle when the vehicle has been raised. The jack stands per se are used to support the vehicle as opposed to ramps and lifting jacks, which are used to raise the vehicle. Jack stands support the vehicle during the repair process and are therefore designed for stable immobile operation when in use. They do require a degree of adjustability while being placed, depending upon the height of the vehicle axle above the ground or other work surface.
Since jack stands are designed to be of a immobile nature when in use, they do not require screw actuators, and in fact are designed to act as a single element without movement when in place.
The simplest example of a jack stand is a wood block which is moved into place after the automobile axle is raised. Another example of a jack stand is a pipe having one end split into three sections and spread to constitute a base. Both of these types of jack stands exhibit principally low cost. The block, of course, is not adjustable in height, other than its normal dimensions, or by stacking shims, a dangerous practice. Some of the pipe jack stands are adjustable by having coaxial pipes with a pin passing through mating holes in the outer and the inner coaxial pipes. Pipe jack stands, although inexpensive, having three point support usually exhibit a degree of instability and are subject to failure due to the serious discontinuity in the pipe at the point of spreading where stress concentrations exist.